The Australian Weather Forum

Lily » Thu Nov 03, 2011 2:15 pm wrote:David Brown has said the past two nights that storms will head into central areas (Melbourne, at least) come early to mid Sunday afternoon.

I'm inclined to believe him. GFS has held steady all week for storms on Sunday, BoM has been keen on it for the last few days too, so I'm just about convinced we'll see some action. Barring some unforeseen shift in the forecast, Sunday will be a full day of chasing...can't wait!

I find it funny how last year a similar GFS output would have been considered normal, these were the sorts of numbers we were getting every run with many events, even upwards of 300mm if I remember right. Good to see them back (minus the flooding potential ).

Finally getting around to looking at the current setup properly, I had my English exam today, I feel very confident with it, one down, four to go!

So on to the forecast analysis. As many of you have already discussed, the upcoming period is looking quite unstable but it is looking quite dynamic as well for next week. We will extend the dates of this thread to fit in next week, as there will be two troughs affecting Victoria quite close together.

Firstly, this Saturday. We will be in a warm to hot northerly airstream thanks to a high pressure system over the Tasman Sea, so things are expected to be generally sunny with temperatures generally at around 30 degrees onwards. There may be some small scale Cu develop in the far west of the state later in the day, as there does appear to be some instability around that region, however conditions are too dry for the formation of any thunderstorm activity plus the trigger is too far away and we would be relying on just surface heating, so as I said, not likely,

Sunday becomes quite interesting with a trough of low pressure likely to enter the west of the state during the late morning, through central parts during the mid-afternoon, and into eastern parts generally at night. Now the timing of the trough has been changing a fair bit with each model run, so it still could change, but that's what i expect for now. Nevertheless, conditions are likely to be warm to hot ahead of the wind change, which is most likely going to be fairly shallow, with winds tending more westerly with the change, then southwesterly later on, introducing milder air. Now the conditions in regards to thunderstorm activity on Sunday are looking more traditional to a frontal system, with most variables checking out quite well, and I will look at these again when we get a bit closer. Moisture seems to be the limiting factor initially though, so we could see dry cell cores to start with, with the development in the west, but as things progress eastwards, precipitation cored cells will be a focus.

Activity contracting eastward on Monday with the trough, so eastern districts likely to be favorable for any shower/storm activity. Elsewhere is likely to be generally fine with a more moist warm day returning.

Dynamic weather situation on Tuesday and Wednesday with low confidence in models. Looks at this stage, though will likely change, that a trough will enter the far west late Tuesday causing storms mostly in the western districts. So something to watch for the.

I will be updating the thunderstorm charts from tomorrow night.

Congratulations!! and good luck !!for your exams Powerstorm and all the other members who have started their VCE exams..Brings back memories.
Just been trying to figure out how this event might pan out.
Started off with the BOM wind forecast map and shows a very complicated wind flow pattern for this event extended into next week. Nothing simple in this trough area .No firm pattern to follow ..Went to the ACCESS synoptic forecast
http://www.bom.gov.au/australia/charts/ ... u&model=CG" onclick="window.open(this.href);return false;
to see if l could make some sense of what might happen. Just generally the west of Vic commences in a trough region about 1010hpascals on saturday arvo until Monday when we are briefly in a high region and then Tuesday into Thursday a trough region again.
I particularly liked the drop in barom pressure on the Sunday between 2pm and 5pm. Dropping to around 1005 down south
It would seem we may see some erratic temps.
The general erratic wind pattern for this event and next week indicates,Sometimes the wind blows north with a cool westerly s/west change arriving and then back again to some northerly breezes and then back again for a change . It would seem we would mainly be in a trough area for most of the time from Saturday to at least next Thursday with a short reprieve of a high influence on the Monday.
The dew point forecast is the most interesting for parts of VIC. Some parts of the state apparently achieve dew points around 20 deg c just like the tropics.
Tuesday and Wednesday being most promising on the dew point variable.
Especially 5pm Wednesday a dew point of 20 deg c from Melbourne to the border and surrounds.Excellent!!
Even 11am the dew point is around 20 -22deg c for nth central and Nth country forecast district.
Wondering how those complex wind patterns of mixing the warm from inland and cold air from southern ocean and the high dew points will pan out.
In conclusion, this is going to be a fantastic weather watch.
This is quite a complicated set up for Vic because of the tussling of low and high cell movement over VIC and if you blur the boundaries of the variables it encompasses all of VIC and makes pinpointing hot spots very difficult.
Myself.. l am going with the dew point map for a guide to hot spots. I think..LOL
http://www.bom.gov.au/australia/charts/ ... u&model=CG" onclick="window.open(this.href);return false;

If those 20 deg dew points came off and then we get a cold front with some cold air in behind it, we could be up for huge storms.

Latest GFS for Wednesday is absolutley off its head. 90% supercell probability lol. Has to happen in the middle of the week when im stuck behind a desk.

Meso » Fri Nov 04, 2011 9:37 am wrote:

Meso wrote:Latest GFS for Wednesday is absolutley off its head. 90% supercell probability lol. Has to happen in the middle of the week when im stuck behind a desk.

Get up past Mansfield middle of next week I reckon...gonna be some great storms

Powerstorm if the quality of your written posts is anything to go by, you should romp it in for English - all the best for your exams anyway!

And back on topic, yes it's looking more and more likely we'll have a major rain event (even flood event) around mid week. The only question is exactly where in Victoria the system bombs, and how hard. Local catchments are pretty saturated here with even the smallest headwater gullies still flowing.

Meso » Fri Nov 04, 2011 10:37 am wrote:

Meso wrote:Latest GFS for Wednesday is absolutley off its head. 90% supercell probability lol. Has to happen in the middle of the week when im stuck behind a desk.

Perfect, no exams that day

NE Vic Wednesday

GFS right onto this. Big HP storms over Central very possible now. Wed arvo looks massive.

Okay.. If i am working next Wed i will be very angry

Even tuesday should see widespread storms.

Wednesday looks ridiculous...every parameter is maxed out. Even the shear is good for here.

I'm predicting a massive wedge to tear through the center of the state. Nah, should see some good storms tho...just wish I didn't have to work Hopefully something about on Sunday to scratch my itch!

Finally looking like a good storm day on a day off!! Wednesday, I will be on the road!
Peter:D

A Tornado will be possible if a big supercell gets up. As Meso said everything is maxed out eg Supercell probability of 80+.

Huge model shift in the past 36 hours or so. Looks good for upwards of 45mm for here now. I feel that widespread totals of over 50mm are probable in vast areas of the state now. Looks like the good old days of 2010 are back!

Hopefully any severe thunderstorms action on Wednesday will hold off until late in the afternoon... I'll be seeing Love Never Dies in the City around mid-afternoon and I would hate the idea of a nasty storm coming through while I'm stuck in the theatre

Hopefully also there'll be some clearance on Wednesday afternoon; the forecast calls for rain periods and the idea of imbedded storms doesn't sound all that flash, but even if something similar to September 28 (such as a squall line) takes place I may end up surprised

Anyway, my attention is focused more immediately on Sunday arvo/evening

Wind forecast map has updated and a reasonably sharp front line ( wind change line) is evident on Sunday crossing Victoria
http://www.bom.gov.au/jsp/watl/wind/index.jsp" onclick="window.open(this.href);return false;
4.00am Sunday morning a low pressure belt westerly ish wind change ( from northerlies) appears to arrive in the western quadrant of the state, on a north /south line.
10.00am Sunday morningBy 10.00am the westerly wind change has already pushed into central quadrant of vic and is a line from Melbourne/Bendigo to Murray.Melbourne appears to have some higher winds on this change.
By 4pm the change has well and truly advanced into the east of the state.
So generally a fast moving front line but everyone gets it.
For a weather watch l am particularly interested in thunderstorm development in the early morning( 4.00am) in the west when RH is possibly around 95% and the front when it reaches the east when the RH is lower.in the afternoon.?
WZ synoptic commentary is suggesting quote
"Sunday 22:00 EDT
Very warm northwest winds will push into NSW ahead of a front and trough. This frontal system will generate widespread showers and storms through VIC, NSW and QLD. A high will clear much of SA, while another trough spreads showers into southwest WA."
Issued Friday 12:03 EDT
http://www.weatherzone.com.au/synoptic.jsp?d=2" onclick="window.open(this.href);return false;
Their synoptic chart for Sunday shows a very tight trough in between 2 highs.
I am hoping to wake up to some dampened ground on Sunday morning. and maybe some storms in the early morning hours for us in the NW central
Reckon could be ok for Melbourne? . I remembered last time ( recent event)northerlies funneled through Melbourne ahead of a westerly change with some nice rain and storms. Wondering if an arrival of 10am to the west of Melbourne and passing Melbourne lunchtime will have a different impact